*** many thanks to Neil Rooney for this blog post ***

I am a firm believer that there is a purpose to every experience in life. No matter how harsh or unfair things seem at the time there is always something to be learned from an experience once you come out the other side.

If you've ever "hit the wall" in an endurance race, you should have learned that you were unprepared and that you made a beginner's mistake. If it has happened more than once you need to do some research on training and nutrition. And if it's a regular occurrence when you train or race you should seriously think about becoming a couch potato because that's probably a healthier way of living. Let me explain!

The phenomenon of "hitting the wall" happens when you have exhausted the body of its glucose stores to the point where you've bonked and still haven't refueled with carbohydrates. The muscles are relying on the fat stores as an energy source (which is a good thing), but remember fats are very slow burning and the 3 energy systems (see post on bonking) are active all the time. So when the glucose stores are exhausted the easy burning fuel system requires something else to burn. The next easy option fuel source is protein, it's not as easy to break down as carbohydrates but it yields the same amount of energy per calorie, so not a bad substitute.

We never have to worry about our fat stores running low because we are so well equipped at storing fat we can never deplete the stores no mater how far we run or bike. Even elite athletes who race between 3%-4% body fat, it's impossible for them to deplete their fat stores. However in order to keep the fat burning process in operation we need some easy access fuel too. So the body must start to burn proteins in the absence of carbohydrates.

We all know that proteins are what we use to build our bodies. Proteins are an enormously important nutrient and they have far more important functions than building strong muscles. All the hormones in your body are proteins in one form or another, the receptors on cells that receive these hormones are proteins, neurotransmitters (responsible for movement and feelings), immune cells (that fight infection), and inflammatory cells (part of the repair process after training) are all proteins and have a huge role in the body.

When you use protein as a primary fuel source such as when you've "hit the wall" you are jeopardising every system in the body which relies on protein. Some hormones and especially neurotransmitters are very short lived, some have a shelf life of less than a second so our bodies are constructing these proteins all the time with the amino acids (the building blocks of protein) that are stored in our liver. We don't have the capacity to store many amino acids due to their acidity so it won't take long to run low on protein stores too. At which point your body will really begin to fall apart from the inside out. When this happens you will feel like you have run into a wall hence the term " Hitting the wall!"

This can happen for two main reasons; poor preparation and inadequate training or inadequate fuel replenishment on race day as a result of poor nutrition.

The common habits of a novice marathon runner or triathlete is to skip breakfast for fear of stomach cramps during the race. Instead is backed up with a pocket or bum bag full of energy gels and energy bars. The race begins and so does the sugar roller coaster. If your training has been inadequate for your desired time you won't have the mitochondrial density (power stations for burning fats) to access the energy required from fats, so you over- rely on sugar. Until the sugar runs out! You will feel really sick (or perhaps have been sick) from downing all the gels and the only option for the body is to burn protein. By mile 20 (in a marathon) you'll know all about that wall!

It will probably take 1-3 weeks to recover from this experience and you may get bombarded with a throat or chest infection days after the race as a result of your immune system (defence army) being depleted.

I hit the wall in the first marathon I ever did in 2001 and haven't revisited the experience since. What amazed me most that day was the participants' ability to jog home after the race. I was so beaten up I could hardly stand and here were these guys jogging home after beating me by an hour or more. That's when I knew I had got something wrong,,, very wrong.

Our involuntary (autonomic) nervous system has a sympathetic component (fight or flight) and a parasympathetic component (rest and digest). These two systems work on a see saw motion, if one goes up in activity the other must go down. On race morning the sympathetic system is on over drive which is why you feel nervous, digestion is turned down which is why you feel butterflies in your stomach. It's a good idea to eat a wholesome oatmeal breakfast with some nuts for slow energy release 3-4 hours before the race. It will take a little longer than usual to digest (due to low parasympathetic activity) but you will reap the benefits during the race. After the 45 - 60 minute point of a marathon and after the swim in a triathlon start to refuel with whatever works for you but be advised simple sugars at this point are not the best option. The fuel source should be carbohydrate and slow releasing. Get inventive and find out what works for you. I like sweet potatoes, dates and bananas.

If on race day you are close to your desired time in the final 5km but feeling low on energy by all means crack open the gels and sugar drinks, they will work wonders to get you home, just don't depend on them from an early stage, they will let you down.

Overall preparation, be it mental, physical or nutritional readiness are essential for a race like a marathon or triathlon. The body must be able to endure the mental stress of wanting to quit, the physical battle to carry on and the fluctuating energy levels that occur during endurance sport. If you are not prepared for all three, you are setting yourself up for failure.

Find a training plan that fits into your life, set a goal, stick to the goal and go for it on race day. No matter how good you feel, stick to the plan unless with 5km to go you still feel great; then you can take off and beat the goal. Rehydrate with water at every opportunity and refuel as you need it. Enjoy the experience and remember there is always another race!